Successful use of the indirect method of dentistry involves equipping a dental articulator so as to accurately represent the chewing mechanism of a particular patient. Simulating the tooth structure with dental models or casts has long been a well-known procedure. It has also been well-known to utilize a transfer face bow for aligning the casts in the articulator. Simulating the action of the temporomandibular joints, however, has been a far more difficult and complex problem.
When the jaw movement characteristic of a patient is measured outside his head, the information as measured appears in a strange mixture of amplified and diminished magnitudes. The information must be reconverted in order to return its various portions to their original magnitudes, or nearly so, depending upon whether or not the "intercondylar width" of the patient is to be precisely reproduced in the articulator. The work of Robert L. Lee, D.D.S., of Colton, California, has established that this reconversion can be performed as an analog computation function. This work is described in Dr. Lee's articles in the August and November, 1969 issues of The Journal of Prosthetic Dentistry; and in U.S. Pat. Nos. 3,452,439 and 3,694,919.
The concept has also been advanced that it is unnecessary and uneconomic to precisely reproduce the "intercondylar width" in the articulator, and that it is instead preferable to utilize a pair of simulated fossae having a fixed lateral separation therebetween. The use of this concept in conjunction with Dr. Lee's analog reconversion procedure has been described in the publication "The Dentonamics System -- January 1973" published by Dentonamics Corporation of Inglewood, California.
The present invention assumes that the jaw movement characteristic of a patient can be accurately recorded, either in mechanical form as shown by Dr. Lee, or in electronic form as shown by the work of others. The present invention is concerned with the mathematical theory of the information reconversion, and with providing an analog module as the most economical mechanization both for receiving the reconverted information in the reconverter and then for subsequently replaying or reproducing that information in the articulator.